Tipulidae, often called crane flies in their adult stage, is the largest family of true flies.  Crane flies form a highly diverse group of insects, both in number of species and in larval habitats, which extend from aquatic to terrestrial.  The body plan or morphology of crane flies is rather simple.  An elongate body, one pair of narrow wings, and long, slender legs characterize them.  The body size ranges from 5 to 50 mm and can be described as mosquito-like.  They are often mistaken for mosquitoes, but they belong to a group of harmless flies and can be distinguished from all other true flies by the transverse V-shaped groove on the dorsal part of the thorax.

In North America, more than 1,500 species of crane flies have been described and over 300 species are known from Pennsylvania.  This number probably represents only about two-thirds of the estimated actual number for the state, and much more precise taxonomic studies are needed.

Crane flies undergo complete metamorphosis in their development with a brief egg stage, a relatively long larval feeding stage, a brief pupal resting stage, and finally a short adult breeding stage.

Crane flies serve several important roles in the ecosystem.  Most importantly, adult and larval crane flies are food for many animals such as birds, fish, frogs, lizards, spiders and other insects.  In addition, the larvae are detritus feeders that break down organic matter in various habitats such as streams and forest floors thereby enriching the soil, renewing and modifying the microhabitat for other invertebrate species.  Some crane flies require special habitat conditions, and their presence or absence can be used as an indicator of environmental quality.  Fishermen use larvae of some large crane flies as bait.  Several species of crane flies are important agricultural pests; their larvae feed on seedlings of field crops and if abundant can be destructive to lawns, rangelands, rice fields, and golf courses.

Male of Epiphragma fasciapenne. by Bruce Marlin	Female of Epiphragma fasciapenne. by Steve Marshall	Prepared Epiphragma fasciapenne

ADULTS: Adult crane flies are sluggish fliers and are often abundant in moist woodlands and around water, usually near places where their larval life is spent.  They occur mainly in spring and fall, but species of wingless, snow crane flies (Chionea) appear in the winter.  Adult crane flies are most active in the cooler part of the day, usually around dusk.  Adult males are more abundant at the beginning of the flight period while females are more numerous toward the end.  Although individual adults have a relatively short life span of 10 to 15 days, the flight period for each species can last from 25-30 days.  The main functions of the adult stage are mating and egg-laying.  Feeding is less important, and probably water is the most pressing need. Species with elongated rostrum (Geranomyia, Elephantomyia, Toxorhina) have been reported visiting flowers, probably for nectars.

Limonia (Geranomyia) rostrata by Richard Leung	Limonia (Geranomyia) communis by Robin McLeod	Limonia (Geranomyia) sp. by Lew Scharpf

Some large sized adult crane flies can be easily sexed in the field.  The outline of the male caudal abdominal segments is expanded and round.  In contrast the female has a tapering abdomen that terminates with an acute ovipositor.  In addition, they can also be sexed by their flight pattern in the air. The males have an erratic flight pattern of undulations and spiral rotations.  Females maintain a more direct, steady and straight flight path.

Tipula ultima - Male ©2005 Chen Young	Tipula ultima - Female ©2005 Chen Young	Pedicia albivitta - Male ©2005 Chen Young	Pedicia albivitta - Female ©2005 Chen Young

LARVAE: The larvae are found in a wide variety of habitats, varying from strictly aquatic to terrestrial, even relatively dry soil.  Their habitats include fresh water in fast-flowing streams, marshes, springs, meadows, seeps, tree holes, algal growth or mosses on rock faces near water, organic mud and decaying vegetable debris along the shores of streams and ponds, accumulated decomposed leaves and rotting wood on the forest floor, and occasionally soil in lawn and pastures.

Photo taken by Marlin E. Rice

The typical shape of mature crane fly larvae is elongate, tapering gradually toward both ends.  The skin is thin, tough, and usually covered with microscopic hairs.  The head is fairly complete and can be retracted into the thorax.  The posterior end has a single pair of spiracles surrounded by a disc of fleshy lobes (spiracular lobes), and membranous lobes (anal papillae) surround the anus.  The shape, length, and number of these lobes vary among species and have proved to be taxonomically important and can be used to identify them.  There is probably a close correlation of structure to habitats. Most crane fly larvae breath air through the posterior spiracles.  Some can remain submerged in water for a limited time period when their habitats become flooded.  The lobes surrounding the posterior spiracles often have a fringe of fine hairs that entrap a film of air when submerged.  A few genera have truly aquatic larvae, which close the tracheal system completely and exchange of oxygen takes place by diffusion through the cuticle of tracheal gills.

Larvae are the growth stage and the majority of crane fly larvae are scavengers feeding on decomposing plant material and the associated microorganisms.  Larvae of some aquatic species are predators on other small invertebrates, and several are herbivores on algae, moss or herbaceous plants.

Spiracular area of Tipula (Angarotipula) illustris larva	Spiracular area of Leptotarsus (Longurio) testaceus larva	Spiracular area of Dolichopeza (Oropeza) walleyi larva
illustrated by Chen Young	illustrated by Chen Young	illustrated by Chen Young
Spiracular area of Tipula (Nippotipula) abdominalis larva illustrated by Chen Young	Spiracular area of Brachypremna dispellens larva illustrated by Chen Young	Spiracular area of Nephrotoma virescens larva illustrated by Chen Young

 

Fishermen have long used both adult and larval crane flies as natural bait for fishing.  They have experience in identifying several common aquatic and terrestrial crane flies and their larvae along streams.  Artificial fly-fishing lures can be found that match several species of these crane flies.

Fly by John Henry	Tipula trivittata by Harriet Fell

NATURAL PREDATORS:

Being a group of clumsy fliers and sluggish maggots, adult and larval crane flies become easy prey for a wide variety of vertebrate and invertebrate predators. Many species of birds can be commonly seen returning to the nestlings with a mouth full of crane flies.

Photo by Chuck Musitano	Photo by Moses Martin	Photo by Frode Falkenberg

Photo by David Jones		Photo by David Jones
Photo by C. E. Timothy Paine Gecko feeds on Nephrotoma sp.		Photo by Scott Hasinger Frog feeds on Tipula caloptera

Spiders, predacious insects, and even carnivorous plants also readily feed on adult crane flies. 

Photo by Jim McClarin	Photo by Herschel Raney	Photo by Graham Checkley

Photo by Ron Hautau	Photo by Werner Eigelsreiter	Photo by Randy Rhine

Photo by Thomas of Baltimore Ectemnius wasp on Nephrotoma ferruginea	Photo by Stephen Cresswell Empis deterra on Tipula submaculata	Photo by Steve Mattan Jumping spider on Nephrotoma ferruginea

Photo by Barry Rice	Photo by Beatriz Moisset	Photo by Anonymous

Photo by Marshal Hedin Protolophus singularis feeds on Tipula sp

PHORETIC ASSOCIATIONS:

Several species of pseudoscorpions and mites have been reported to attach themselves to crane flies.  The majority of these associations are actually phoretic relationships, where the pseudoscorpions and mites are carried as hitchhikers by the crane flies.  However, others are parasitic mites that feed on the body fluid of the crane flies.

Epiphragma fasciapenne with pseudoscorpion Photo by Jay Cossey	Tipula fuliginosa female with mite    Photo by Tom Murray	Tipula ultima with mites                    Photo by Jay Cossey

Tipula borealis with mites       Photo by Tony DiTerlizzi	Pseudolimnophila species with mite         Photo by Tom Murray	Tipula ultima with mite       Photo by Jay Cossey

PARASITIC ASSOCIATIONS:

Crane flies have also been found as victims of the parasitic fungus Entomophthora.  Species in this genus such as Entomophthora muscae is the common pathogen that causes fungal disease in a wide range of adult flies and eventually kills them.  The following image illustrates the typical posture of an infected crane fly (probably Tipula (Lunatipula) group) with spreading legs and wings, and the bloated abdomen filled with visible spores between the abdominal plates.  This posture ensures that the fungal spores have the best possibility of dispersal and host infection.  Because insect-pathogenic fungi usually require moisture to enable infection, this infection usually occurs during the wet or humid spring and fall of the year in our region.

Tipula sp. infected by Entomophthora fungus   Photo by Judy Semroc

Recent field research by Carnegie Museum entomologists David Koenig and Chen Young has discovered an unusual parasitic relationship between a group of Big-headed flies (family Pipunculidae, genus Nephrocerus) and adult crane flies.  Nephrocerus atrapilus and Nephrocerus daeckei were reared as endoparasitoids of three species of adult crane flies in the genus Tipula (Tipula duplex, Tipula mallochi, Tipula submaculata).  Two additional Tipula species (Tipula furca, Tipula tricolor) were observed to host pipunculid larvae presumed to be species of Nephrocerus.  Pipunculid larvae are known to parasitize leafhoppers, particularly Cicadellidae, Delphacidae and Cercopidae.  This study presents the first report of hosts for Nephrocerus, and the first recorded instance of adult crane flies being parasitized by another true fly.

Nephrocerus species Photo by Stephen Cresswell	Tipula duplex female parasited by Nephrocerus sp.     Photo by Robin McLeod	Nephrocerus atrapilus Photo by Chen Young

Our study demonstrated the known host species belong to the subgenera Lunatipula and Yamatotipula within the genus Tipula.  The majority of species of Tipula in our study area are univoltine, and they are common spring and summer elements in habitats of mixed deciduous woodlands of oak, hickory, maple, and black cherry.  Our study also showed that female crane flies are preferred hosts for the Big-headed flies.  The mode of infestation in this study is still unknown.  Further observations on the life history of Nephrocerus are needed, especially of host location and oviposition behavior. The result of this study was published in the Proceedings of the Entomological Society of Washington 109(1):52-65.  Two additional species of crane fly host were observed recently including Tipula valida (Westmoreland County, Pennsylvania) and Nephrotoma ferruginea (Suffolk County, New York, Garrett Herth).

Larva of Nephrocerus atrapilus                      Illustrated by Chen Young	Puparium of Nephrocerus atrapilus                         Illustrated by Chen Young

 

Nephrocerus atrapilus male lateral view                 Photo by Jeff Skevington Nephrocerus atrapilus female lateral view Photo by Jeff Skevington
	Nephrocerus atrapilus dorsal view Photo by Jeff Skevington